In automation technology, electronic control systems are used, in particular, for automating technical processes. Conventional electronic control installations have so-called decentralized (distributed) peripheral equipment. This entails electrical process signals being routed, for example from a central programmable computer unit, particularly a programmable controller, via a bus system to control installations having a decentralized design. Such electronic control systems, capable of having a decentralized design, no longer require, in particular, signal lines to be wired centrally in control (switchgear) cabinets, since decentralized, modular terminal blocks can be installed at any desired point in the process to be automated.
European Patent No. EP 0 323 579 describes a decentralized input/output module for electronic control systems. In the middle of this module, a central connector terminal box is provided. On both sides of the connector terminal box, insertion input and output modules can be attached in mirror symmetry around its center line. A plurality of plug connectors are provided on both sides of the central connector terminal box for contacting the input and output modules.
German Patent No. 44 38 806 describes a modular control installation, where connection blocks which are capable of being mounted side-by-side on mounting rails provide signal processing between field devices and an internal bus conductor. In this context, the internal bus conductor can be coupled to a higher-level field bus system. The modular control installation has fixed (modular) terminal blocks adapted to receive a plug-in electronic module. The removable electronic module is used, in particular, for signal processing purposes and is designed to be coupled to a bus system linked to a programmable controller.
The design described in German Patent No. 44 38 806 is disadvantageous because the layout of the terminal region requires a large area and is disorganized, and the attachable electronic module projects upwards to a large extent. Also, the terminal blocks, which lie one above the other in a number of rows, present an extremely confusing wiring appearance. This has the drawback of increasing the rate of wiring errors, and the time needed to plan and design wiring for the control installation.